D'ailleurs

[Crack1]

Tu n'aimes pas l'opéra, et d'ailleurs l'interprétation n'était pas bonne.

You don't like the opera and moreover the rendition was not so good.

You don't like the opera because the rendition was not good.

The French word ' d'ailleurs' means moreover.
However, I have difficulty in translating the French sentence into English.
Please help me.

[Frank]

Hello Crack,

"d'ailleurs" can also mean "by the way" ("au fait"). It's also sometimes used as "to top it off" ("de plus").

[Neil Coffey]

I think "moreover" is fine, just that it's slightly formal. You could also try "and what's more...".

Especially when you see "d'ailleurs" at the end of a sentence, a translation that can sometimes work is "for that matter" (I think Frank's suggestion of "to top it off" is also good, although more informal).

[Crack1]

I thank Frank and Neil for the replies.

You don't like the opera because the rendition was not good.
On reflection I found the above is not very accurate.
It should be the following:

You didn't like the opera because the rendition was not good.

Tu n'aimes pas l'opéra, et d'ailleurs l'interprétation n'était pas bonne.
Is the above grammatically correct?

I think the following is the correct one.
Tu n'aimais pas l'opéra, et d'ailleurs l'interprétation n'était pas bonne.

[Frank]

Tu n'aimes pas l'opéra, et d'ailleurs l'interprétation n'était pas bonne.
Is the above grammatically correct?

Yes it is.

I think the following is the correct one.
Tu n'aimais pas l'opéra, et d'ailleurs l'interprétation n'était pas bonne

Well, there's no reason to change the present to the past.